The present invention generally relates to semiconductor devices and more particularly to the fabrication process of a semiconductor device in which a capacitor and a resistor are integrated.
Conventionally, semiconductor devices are used in which semiconductor device elements such as transistors are integrated on a semiconductor substrate together with capacitors and resistors. With such semiconductor devices, the capacitors are formed by utilizing trenches formed in the semiconductor substrate, while the resistors are formed as a polysilicon pattern on the semiconductor substrate.
With the capacitor of the type thus formed by using the trench formed at the surface of the semiconductor substrate, an oxide film is formed on the trench surface as a capacitor insulation film, and a polysilicon pattern is formed as a top electrode such that the polysilicon pattern fills the trench via the oxide film. With the capacitor of such a construction, there is a need for providing high conductivity to the polysilicon pattern filling the trench by doping with an impurity element to high concentration level up to the part filling the trench bottom.